What does hydroxymethylbilane synthase do?

Human hydroxymethylbilane synthase (hHMBS) is a monomeric enzyme that catalyzes the stepwise head-to-tail condensation of four porphobilinogen (PBG) molecules to form the linear tetrapyrrole 1-hydroxymethylbilane (HMB). Mutations in the hHMBS gene cause autosomal-dominant acute intermittent porphyria (AIP).

What is the Hmbs gene?

The HMBS gene provides instructions for making an enzyme known as hydroxymethylbilane synthase. This enzyme is involved in the production of a molecule called heme. Heme is vital for all of the body’s organs, although it is most abundant in the blood, bone marrow, and liver.

What is the most common porphyria?

Porphyria cutanea tarda (PCT) is the most common type of all the porphyrias. As a result of sun exposure, you may experience: Sensitivity to the sun and sometimes artificial light, causing burning pain.

What does Porphobilinogen deaminase do?

Porphobilinogen deaminase is involved in the third step of the heme biosynthetic pathway. It catalyzes the head to tail condensation of four porphobilinogen molecules into the linear hydroxymethylbilane while releasing four ammonia molecules: 4 porphobilinogen + H2O.

Is Porphobilinogen a porphyrin?

Urine porphyrins are useful for the evaluation of cutaneous photosensitivity to exclude porphyria cutanea tarda (PCT). Urine porphobilinogen (PBG) is useful for the evaluation of neurologic and/or psychiatric symptoms to exclude acute porphyrias such as acute intermittent porphyria (AIP).

What is Gunther’s disease?

Congenital erythropoietic porphyria (CEP or Gunther disease) is an extremely rare subtype of the non-acute group, estimating a prevalence of <0.9 in 1 000 000 [1, 2]. All organs are vulnerable to the porphyrin accumulation effects, but the most affected ones are the skin, hematopoietic system, teeth, bones and sclera.

How is porphobilinogen detected?

Urinary porphobilinogen (PBG) is ideally measured during an acute porphyric attack as a random spot test. Twenty-four–hour levels may also be obtained. The sample should be collected with a urinalysis container or 24-hour urine container.

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